In reality, there is evidence for multiple accretion components in observations, in agreement with simulations (e.g. [1]}, [2]}, [3]}), but our assumption of a constant local accretion rate and an infinitely sharp transition between the accreting and the non-accreting region is a minor one.
Also, given that very edge-on systems are less likely to be detected or observed, there is a relatively large probability of viewing the planet indeed within
\(45{\mbox{°}}\)  of pole-on. Therefore, we assume that the radiation is travelling only radially (i.e. away from the planet) through the accretion region towards the observer,
and neglect the possibility of scattering out of the accretion cone into the line of sight towards an observer not looking down into the accretion cone.
